I've traveled with my son a few times between ages 1 - 2.5, some of them one-adult trips, although all were before covid-19. It's tough but doable.
I did talk to my son about what would be involved in the trip-- going through the security, getting on the plane, sitting in our seats, going up in the air, etc. I think it was helpful to some extent, but sitting still for an extended time is more a matter of impulse control than understanding, so it helped more with being excited about the trip and not scared than it did for reducing his desire to climb all over the place!
My advice-- Your toddler will sooner or later find a way to touch something gross, no matter how conscientious you are. You are going to need a lot of hand sanitizer. If you can get one of the foam ones, I find it a lot easier to apply to little hands without mess. The liquid spray is also a good choice, with the typical gel style being the messiest in my experience. If you haven't yet, practice using hand sanitizer a few times before you go, just so you aren't piling on one more brand new experience. Try to get a scent and/or packaging your child finds appealing.
To reduce the amount of touching things you can't easily sanitize, I would try bringing an old, twin size fitted sheet to use as a seat cover for your child's airline seat. Also bring as many as possible of your own snacks/food and anti-spill toddler cups, to reduce having to get food along the way.
Some people say that will power is a limited resource, and for kids this definitely seems to be true. Try to reduce temptation and willpower usage on things other than the 'don't touch' imperative. Carry her or have her stay in the stroller, suitably entertained, until it's time to board the plane. This isn't the time to worry about screen time. If the tablet is what keeps your kiddo from crawling around on the airplane floor, use it. Eat unlimited snacks, let her wear pjs all day, whatever small policies can be suspended for the duration of the trip so your little one can use all of her age-limited willpower and impulse control to not run around and touch all the interesting stuff.
Finally, general toddler travel tip-- the ear pressure on takeoff and landing can be very uncomfortable for little ears. A chewy snack or drinking through a straw can help them pop their ears, or try encouraging you child to yawn to relieve the pressure. Telling and acting out a story about all her favorite animals stretching and yawning before going to sleep can be a good way to get little ones to cooperate with this.